Random Row Sampling Query | Dataford Interview Questions

A large product catalog needs an efficient way to retrieve one randomly selected catalog row without sorting the entire table. Write a PostgreSQL query that returns exactly one row from big_table while avoiding a full-table ORDER BY random() operation.

Output

Return at most one row with columns id and name.
Select the row through an efficient sampling strategy, with a fallback for cases where the primary sampling method returns no rows.
Preserve NULL values in name when the selected row has no name.
Return no rows when the table is empty.

Schema

big_table

Column	Type	Description
idPK	INTEGER	Unique catalog row identifier
name	VARCHAR(200)	Catalog item name

Your question is Random Row Sampling Query. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Output

Return at most one row with columns id and name.
Select the row through an efficient sampling strategy, with a fallback for cases where the primary sampling method returns no rows.
Preserve NULL values in name when the selected row has no name.
Return no rows when the table is empty.

Schema

big_table

Column	Type	Description
idPK	INTEGER	Unique catalog row identifier
name	VARCHAR(200)	Catalog item name

Your question is Random Row Sampling Query. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.